I mean, a Built b-series bottom end will run about 1200?

400 - pistons
350 - rods
50 - bearings
100 - blockguard
200~ machinework

and then you have a bseries bottom end more than capable of handling 400+ hp
a stock gsr or b16 head ( possibly some gsr or type r cams, springs, rets)

and a good turbo setup. (peice one together for 1000-1800$)

Basically the same setup I had is the one described above and it made over 400 on 17lbs, Daily Driven. and was one of the fastest street cars in the area

or

a stock b16 with some gsr cams and the same turbo setup. (ramhorn mani, .60 trim turbo, 3 in charge pipes, 38 wastegate, etc, etc. made 275 on 8lbs.

Its up to you.